The present invention relates to telescopic conveyor systems, and in particular to support assemblies for telescopic conveyor systems.
Telescopic conveyor systems are commonly used to transport materials from one location to another location. Typically, telescopic conveyor systems have a frame which includes an elongate extendable frame mounted for reciprocal movement on an elongate base frame. Reciprocal movement of the extendable frame is usually facilitated by a number of rollers which are mounted directly on either the base frame or the extendable frame and which travel along guide tracks. Examples of extendable conveyor systems can be seen in U.S. Pat. No. 3,378,125 issued Apr. 16, 1968 to Fogg, U.S. Pat. No. 3,825,107 issued Jul. 23, 1974 to Cary et al., and U.S. Pat. No. 5,351,809 issued Oct. 4, 1994 to Gilmore et al.
In recent years, mobile telescopic conveyor belts have seen use in very heavy industries such as the aggregate industry where mobile conveyors are used to construct non-segregated stock piles of aggregate materials. Telescopic conveyor belts used in the aggregate industry are generally larger than those described in the above mentioned patents, and have an elongate base frame with a rectangular cross-section which telescopically receives an elongate extendable section having a smaller rectangular cross-section. By way of example, the Thor Aggregate Equipment Division of Thor Steel And Welding Ltd. of Mississauga, Ontario, Canada produces and sells a telescopic conveyor system for use in the aggregate industry known as a Telescopic Portable Radial Stacker which, in one version, has a retracted length of approximately 82.5 feet and an extended length of approximately 136 feet. In order to adequately support the extendable frame, a number of parallel, spaced support rollers are typically located at the bottom side of the outward end of the base frame for engaging the underside of the extendable frame, and a number of parallel, spaced support rollers are located at the top side of the base frame, some distance from the outward end of the base frame, for engaging the top-side of the extendable frame. In the past, these support rollers have all been mounted on the base frame independent of each other. Given the weight and size of the extendable frame, and the weight of the aggregate load it is used to transport, the extendable frame will typically deflect to a certain degree of curvature along its longitudinal axis when extended. The degree of curvature will vary depending on, among other things, the size of the conveyor system, the load carried, and the extent that the extendable frame is actually extended at any given time. As a result of this curvature, it has been difficult to provide adjacent support rollers which each bear a proportionate share of the weight of the extendable frame. For example, when the extendable frame is in its fully extended position, its curvature could result in the support roller located closest to the outward end of the base frame bearing substantially the entire weight of the extendable frame while an adjacent support roller was subjected to a disproportionately lighter load. As a result disproportionate stresses are concentrated on one support roller, and on the location of the extendable frame that is engaged by the support roller. Such a configuration requires that stronger and more materials be used in the construction of the conveyor frame to compensate for these disproportionate stresses, and additionally may reduce the lifespan of the support rollers.
It is therefore desirable to provide a support assembly for a telescopic frame which provides for a proportional distribution of weight across a number of adjacent support rollers regardless of the curvature of the extendable frame. It is also desirable to provide a telescopic conveyor belt system which has such a support assembly.